The 5 ‘W’s of Diffusing

Diffusing essential oils at home is a wonderful and effective method to benefit from the various therapeutic properties of essential oils. For example, you may choose essential oils that are uplifting and revitalizing to diffuse during the day and others that are calming and relaxing in the evening. Diffusing essential oils during the cold and flu season is a great way to prevent the spread of germs and cleanse the air of airborne particles that may be harmful.  

But did you know there are safety issues to consider when diffusing?

This 4 part article discusses the ins and outs of diffusing using a water-filled ultrasonic aromatherapy diffuser for therapeutic purposes (and not simply to ‘fragrance’ the air). 

Here are the highlights: 

  • Choose your essential oils with care - consider who is sharing the air space
  • Always use a timer
  • Diffuse in 30-minute intervals
  • Clean your unit regularly

What is a Diffuser?

Remember the candle-warmed bowls that would gently warm the water

and release the aroma of your chosen essential oils? Diffusers have come a long way!  The term diffuser refers to any device that has the capacity to release the aroma of essential oils into the air (e.g. diffuser jewelry, plug-in car diffusers, those that use water etc.). 

An ultrasonic aromatherapy diffuser refers to a particular type of technology.  This type of diffuser is an easy, efficient and affordable way to diffuse.  The special technology found in the ultrasonic diffuser is the small steel plate at the base of its bowl, that vibrates, combining water and essential oils into a fine, cool mist that is then released into the air through the diffuser’s hood.  The ‘bowl’ is what holds the water; and the ‘hood’ is the lid to your ultrasonic diffuser. 

While heat-generating diffusers (like the candle-warmed bowls) quickly deteriorate, evaporate, and often change the aromatic profile of an essential oil, an ultrasonic (or water filled) diffuser maintains the integrity of an essential oil — meaning that the therapeutic properties and chemical constituents of the essential oil(s) are preserved. 

While diffusing might seem simple, even common sense (and it is), there are important safety issues to consider when diffusing. 

The 5 ‘W’s of Diffusing

  1. Who shares the air space? 

Pets need ‘escape routes’ since their sensitive noses can become overwhelmed by the diffusing aromas.   Furthermore, the mist, which contains essential oils, may land on your pet and their fur - which they then may lick and inadvertently ingest. Cats in particular, lack the necessary liver enzymes to break down essential oils, and should not be in a small closed room while diffusing. (Check out the Canadian Veterinary Medical Association for important safety information in regards to pets and essential oils).

Babies and young children who cannot easily communicate discomfort need to be monitored for adverse effects of potential over exposure to essential oils.  Adverse effects may include nausea and headache.  In order to be as safe as possible, do not diffuse around babies or if you are nursing (as you inhale the essential oils, these are now in your system and may be passed on to your baby via breast milk). 



Anyone with a pre-existing health condition (e.g., someone with asthma, COPD, high or low blood pressure) should be considered when choosing to diffuse or not to diffuse and when choosing which essential oils to diffuse (see below).

  2 & 3. What oils are you choosing to diffuse? And why?

As you either already know, or will quickly learn, some essential oils are much more potent (even in small quantities) than others.  Be clear about how many drops of a particular essential oil to add and its purpose (the ‘why’ of diffusing).  For example, essential oils from the Labiatae (e.g., rosemary, peppermint, thyme etc.) and Myrtaceae (eucalyptus, tea tree, clove bud etc.) plant families pack a potent aromatic punch.  Often one drop will do.  But other essential oils, say from the Rutaceae family (e.g., sweet orange, lime, grapefruit, etc.) are much more gentle on the olfactory system. 

Please take the time to check the safety data for each of the essential oils you are putting into the air by referring to a reputable and trusted author in the field.  You are always welcome to book an appointment with me here.

Keep your expectations in check. If you’re like me and grew up with synthetic ‘air fresheners’ your expectations may be that your ultrasonic diffuser should be smelled across a large room or even throughout your house. When using essential oils for their therapeutic properties, this is neither realistic nor desired. 

Stay tuned for Part 2 where we will finish-up
The 5 ‘W’s of Diffusing. 

Stay healthy and happy. 

 Lisa June Byers
Certified Aromatherapy Health Professional (CAHP)
Blending and crafting in Guelph, Ontario, Canada 

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